Apparatus for the continuous casting of metal



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APPARATUS FOR THE CONTINUOUS CASTING OF METAL,

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S. H. JONES APPARATUS FOR THE CONTINUOUS CASTING OF METAL May 23, 1967 Filed Oct. 18, 1963 United States Patent 3,321,0(98 APrAnArUs FOR THE CONTINUOUS CASTING 4M0 W. 111th St, Galilawn, Ill.

Filed Get. 18, 1963, Ser. No. 317,278 9 Claims. (Cl. 164-155) This invention relates to the continuous casting of metals and more particularly to a method and apparatus for the continuous horizontal casting of metal in a new and improved manner.

Ever since the time of Bessemer, who first conceived the idea of continuously casting ferrous metals, the steel industry has grappled with the problems of casting steel into continuous strips, billets, blooms, slabs, and other shapes. To date, the industry has had, at most, only moderate success in developing a method and apparatus for satisfactorily casting ferrous metals continuously. The typical continuous casting machine consists of means for delivering a constant flow of molten metal to a vertically mounted oscillating mold which is water cooled. The molten metal flows into the mold where it is chilled by the walls of the mold and emerges from the bottom as a semi-solid strip. Usually it is necessary to introduce water sprays at the exit end of the mold so as to continue the freezing process of the molten steel center. Below the oscillating mold, there are provided pinch rolls for withdrawing the semi-solid steel strip. Below the pinch rolls, the steel must either be cut off or bent from the vertical into a horizontal position so that it may be run out on tables or cooling baths.

More recently, continuous horizontal casting devices have been developed, but with only a small degree of commercial success.

One of the most pertinent problems in continuous casting of ferrous metals has been the inability to produce strips, billets, blooms and slabs with a good surface quality.

Another serious problem in continuously horizontally casting ferrous metals in a peripherally closed tubular mold has been the frictional drag between the work and the mold wall which frequently causes ruptures or breakouts.

There has also been a problem of supporting elongate horizontal molds having mold walls that are sufficiently thin to effect relatively rapid dissipation of heat from the metal being cast without creating hot spots in the inner surface of the mold wall.

It is a principal object of this invention to provide a new and improved method and apparatus for the continuous casting of metals.

A further object of this invention is to provide a new and improved method and apparatus for casting molten metals continuously in a substantially horizontal position.

A further object of this invention is to provide a new and improved method and apparatus for horizontally casting ferrous metals into continuous strips having an improved surface quality.

Another object of this invention is to provide a new and improved continuous casting apparatus having a single piece tubular mold which is vibrated transversely of its length.

Another object of this invention is to provide a new and improved continuous casting apparatus of the vibrating mold type in which improved means are used to cause vibration of the mold transversely of its length.

It is still another object of this invention to provide a new and improved method and apparatus for uniformly cooling the metal to be cast throughout the length of a relatively thin-walled tubular mold.

It is also an object of this invention to provide a new 3,321,998 Patented May 23, 1967 and improved method and apparatus for continuously horizontally casting degassed molten metals.

A still further object is to provide a new and improved continuous casting apparatus having a constant stream of molten metal emanating from a tundish in which the molding process is controlled by the rate of withdrawal of the solidified billet from the mold.

Another object of this invention is to provide a new and improved continuous casting apparatus designed to minimize the requirement for the development of operating skill.

A still further object of the present invention is to provide an expeditious and facile method of continuously horizontally casting metals.

Further objects, features, and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is an elevational view of a casting apparatus in accordance with this invention;

FIGURE 2 is an enlarged view in vertical section of a casting apparatus in accordance with this invention;

FIGURE 3 is an enlarged view in vertical section of the entry end of the casting mold;

FIGURE 4 is an enlarged view in vertical section of an expansion joint in the apparatus housing;

FIGURE 5 is an enlarged view in vertical section of the exit end of the casting mold and an interrupter valve;

FIGURE 6 is an elevational View of an adjustable stroke interrupter valve;

FIGURE 7 is an elevational view of a modified form of an interrupter valve;

FIGURE 8 is a cross-sectional view taken along line 88 of FIGURE 2; and

FIGURE 9 is a cross-sectional view similar to FIG- URE 8 showing the mold in deflected position.

The casting apparatus in accordance with this invention will be particularly described herein as it pertains to the casting of a continuous steel slab; however, it is understood that the method and apparatus in accordance with this invention may be used to cast a variety of metals and metal alloys as well.

Referring now more particularly to the drawings, there is generally shown in FIGURE 1 a horizontally disposed casting housing at 10. In the form shown, the casting housing comprises a twelve inch steel electric weld pipe securely fastened to a flanged sweep elbow 111 by suitable [means such as bolts 12, shown in FIGURE 3. The inner surface of sweep elbow 11 is lined with a suitable refractory material 14.

A vertically disposed riser, generally shown at 15, comprises a flanged electric weld pipe 16 lined with a suitable refractory material 17 and forms a degassing chamber 18 with a flexible connection 19 to a. conventional vacuum system 20. The function of the vacuum degassing system in connection with continuous horizontal casting of metals will be more fully discussed hereinafter.

The riser 15 carries a tundish, generally shown at 21, for receiving the molten metal to be cast from a teeming ladle (not shown). This tundish is provided for teeming the casting machine and, in the form shown, comprises a forty-eight inch electric weld pipe 22 suitably lined with refractory material 23. The bottom of the tundish 21 is tapered to form a nozzle 24 for providing a constant flow stream of molten metal to the degassing chamber 18.

The tundish 21 is coupled to the casting riser 15 by a conventional expansion joint generally shown at 25.

The casting housing 10, sweep elbow 11, riser 15, and tundish 21 are assembled to form a single unit which is mounted for slight pivotal movement about pin joint 26 carried by support 27. Riser 15 has a pair of trunnions 28 near its upper end. A yoke 29 is provided to engage the trunnions 28 and forms part of a first-class mechanical lever fulcrumed at support 30 to support the structure. The opposite end of the yoke 29 is supported by a load cell 31 which will provide transmission of a signal of the weight being supported by the yoke 29 to an indicator 32 located adjacent to a speed control 33 for controlling the withdrawal rate of pinch rolls 34. This signal indicates to the operator the molten metal level in the riser degasser chamber. By adjusting the withdrawal rate of rolls 34, the level of the molten metal in chamber 18 may be increased, decreased, or maintained constant. Because the weight of the molten metal in chamber 18 tends to force the solidified metal out of the mold, the operator is able to provide any desirable degree of assist to the pinch rolls 34 by adjusting the molten metal level in chamber 15. The proper level is then maintained to obtain good casting results. It is also necessary to control the withdrawal rate so that an adequate chamber volume exists in the degassing chamber to permit the proper degassing operation.

As best seen in FIGURES 2, 3 and 5, there is provided within the housing a substantially horizontally disposed casting mold, generally shown at 35, for casting a continuous metal slab 35. The mold shown at 35 consists of a deformable, thin-walled tube 37 having flanged, open, entry and exit ends 38 and 39, respectively.

In the form shown for casting steel, the mold 35 comprises a copper tube which is supported within the casting housing 10 at its entry and exit ends 38 and 39. As best seen in FIGURE 3, the flanged entry end 38 of copper tube 37 is securely held between the flange-d ends of housing 10 and sweep elbow 11. Similarly, the flanged exit end 39 of the copper tube is rigidly secured at the opposite end of housing 10.

Since the coefficient of thermal expansion of copper is greater than that of steel, an expansion joint, generally shown at 1041: is provided in the steel housing 10 near the exit end 33 of the mold 35 to permit the mold to expand as dictated by the temperature condition that it is experiencing. The expansion joint, as best seen in FIGURE 4, is of a conventional nature and includes an expansible flanged coupling 10b secured between sections of housing 10. A plurality of adjustable tie bolts 10c are provided for limiting the expansion of coupling 10b. The bolts 100 are adjusted to put a slight compression on mold 35 when the mold is at operating temperature to facilitate vibration of the mold.

The wall of the copper tube 37 is relatively thin, thus giving the tube an outside cross-sectional dimension approximately equal to the size of the slab it is desired to cast. As seen in FIGURE 8, the copper mold tube has a substantially square cross section, but it is understood that the tube is not limited to this configuration. The length of the mold 35 is determined by the machine capacity. As an example, in the case of a fifty ton per hour mold for a casting 6" x 6" continuous steel billet, the mold is approximately ten feet long and has a wall thickness of approximately A inch.

The housing 10 and mold tube 37 form a cooling chamber 40 between them. A number of nozzles 41 are provided in the housing 10 near the entry end of mold 35 for supplying a fluid coolant 42 to the cooling chamber 40 for solidifying the molten metal being cast in the mold.

The number and spacing of the nozzles 41 are dependent upon the size and shape of the strip being cast. For example, in casting the 6" x 6 steel billet shown, four nozzles are sufficient, whereas, in casting a 6" x 12" slab, six nozzles are preferably used.

The highest temperature exists at corner 33a (FIGURE 3) of the tubular mold 35 and it is important to have maximum cooling at this point; therefore, the nozzles 41 are directed toward corner 38 to eflecutate maximum cooling at this corner of the mold.

The fluid collant 42 is circulated through the cooling chamber 40 by fluid pump 42a and out port 43 near the exit end of the mold 35 back to heating and cooling tank 421).

Since the copper mold tube 37 has a very thin wall to effectuate maximum dissipation of heat from the molten metal, the mold will not support the molten metal being cast therein in and of itself without being supported intermediate its supported ends 38 and 39. If the thinwalled, structurally weak mold 35 was supported intermediate its ends by attachments to structural members in the housing 10, hot spots would be developed on the inner surface of the mold wall, thus causing uneven heat distribution and a poor quality casting. To alleviate this possibility, the fluid coolant 42 provided has substantially the same specific gravity or density as the molten metal being cast, and therefore, there is no structural requirement on the tubular mold 35 to hold its shape during the casting operation since the mold, intermediate its rigidly supported ends, is merely floating in the fluid coolant 42.

When molten steel, having a specific gravity of about 490 pounds per cubic ft., is the metal being cast, the fluid coolant 42 may comprise a molten mixture of lead and tin having a density of about 490 pounds per cubic ft. In this case, the heating and cooling tank 42b is a more or less conventional tin pot provided to heat the molten mixture of lead and tin, to a temperature of approximately 700 F. for initial startup of the casting operation. Once casting has begun, it is necessary to remove heat at approximately 300,000 B.t.u.s per minute and no auxiliary heating of the tin pot is required. Accordingly, the tin pot is designed with water cooling coils (not shown) inserted in the bath to maintain an exit temperature of the tin pot of approximately 600 F. Approximately 36 cubic ft. per minute of coolant will be required for the operation of a fifty ton per hour machine casting a 6" x 6" steel strip. In the case of such machines, the fluid coolant 42 is provided at a pressure of about 25 psi. in order to overcome the resistance to flow through the cooling chamber 40 and associated piping. The port 43 is located in the bottom surface of cooling chamber 40 and the heating and cooling tank or tin pot 42b is located below the level of the cooling chamber 40 so that the fluid coolant 42 can be drained by gravity in the event of any malfunction.

The cooling action is such that the stream of molten metal introduced into the entry end of the mold 35 is frozen progressively towards its central axis as it is continuously moved through the mold, and it emerges as a solidified slab or billet.

In order to insure that the solidified slab 36 can be successfully withdrawn from the exit end of mold 35, a coolant flow interrupter, generally shown at 45, is provided at the discharge port 43 of the cooling chamber 40. This interrupter serves to establish a controllable series of shock waves in the fluid coolant 42 in the area surrounding the mold 35 for inducing vibration in the mold wall in a direction generally normal to the surface of the strip being cast, as shown in FIGURE 9.

The interrupter 45 comprises a pipe 46 having a fluid passageway 47 therethrough. In a preferred form, a disc or butterfly valve 48 is mounted in pipe 46 for interrupting the flow of fluid coolant through fluid passageway 47.

In the preferred form shown in FIGURE 6, butterfly valve 48 is oscillated between a fully open or partly open position and a fully closed or partially closed position by a variable speed motor 49, gear reducer 50 and adjustable stroke linkage, generally shown at 51. The adjustable stroke linkage 51 comprises a first arm 52 pinned to the valve shaft 53 of butterfly valve 48 and a second arm 54 pinned to arm 52 at one end and to a third arm 55 which is rotated by gear reducer 50. The effective length of arm 55 may be varied by pinning arm 54 to it at different positions for obtaining various degress of valve oscillation.

A modified form of interrupter 45 is shown in FIG- URE 7 where a variable speed motor 56 drives gear reducer 57 having an output shaft 58 directly connected to the valve shaft 53 of butterfly valve 48 for rotating the valve through 360".

In either form of interrupter, the frequency and magnitude of flow interruption can be adjusted over a wide range so as to compensate for variations in coolant temperatures, rate of pour, and the chemistry of the metal being cast.

When the butterfly valve 48 is in the full line position shown in FIGURE 5, a shock wave is transmitted through the fluid coolant 42 to the mold 35 to deform the walls, as shown in FIGURE 9. The deformation is exaggerated in FIGURE 9 for cle-arness. Upon opening of the butterfly valve, the mold 35 is restored to the shape shown in FIGURE 8. Rapid rotation or oscillation of butterfly valve 48 provides a series of rapidly recurring shock waves in the fluid coolant in the area surrounding the casting mold and induces a rapid vibration of the mold wall in a direction generally normal to the surface of the strip being cast, as shown in FIGURE 9. The design provides for a maximum shock wave at the bottom of the mold 35.

The rapid vibration of the mold 35 transversely of its length due to the interruption of the circulation of the fluid coolant forges the strip 36 to a dimension slightly smaller than the inside surface of the mold 35. The vibration also agitates the molten metal as it is proceeding through the solidification process for forming a slab having a good surface quality. This agitation materially aids in the movement of gases of the molten metal as it is being solidified. These gases will move to the top of the mold where they will tend to slow down the rate of cooling of the top surface of the billet 36. In order to minimize the volume of gases which will collect at the top of the mold, the previously mentioned vacuum stream degassing system is provided for degassing the molten metal prior to its introduction into the entry end of the mold.

Vacuum stream degassing, in general, is the release or pouring of a constant stream of molten metal into a moderately high vacuum. The occluded gases within this stream cause it to :burst apart, into a rain of small particles, exposing to the vacuum thousands of square feet of molten metal surface area. It is this vast exposure of the metal in the form of small drops to a high level vacuurn which accomplishes the removal of minute amounts of gases and contaminates which is so important in todays high-quality steels.

As best seen in FIGURE 2, a constant stream of molten metal is provided at nozzle 24 of tundish 21. The stream of molten metal is released into vacuum chamber 18 where it is subjected to a moderately high vacuum. There, the gases within this stream cause it to burst apart, into a rain of small droplets, as depicted in FIGURE 2, thus exposing thousands of square feet of surface area of molten metal to the vacuum for removal of gases.

FIGURE 2 shows that the vacuum degassing chamber 18 is directly connected to the entry end 38 of the casting mold 35. Thus, it is necessary to maintain a head of molten metal in the casting riser 15 in excess of about 35 inches above the elevation of the casting mold 35 in order to insure that there will be no tendency to inspirate air at the exit end 39 of the mold. The level of molten metal in the casting riser 15 must also be controlled by the withdrawal rate of the strip from the mold so that an adequate chamber volume exists in the degassing chamber 18 to permit the proper degassing operation. Accordingly, the weight responsive molten metal level indicator 32 is provided with associated withdrawal rate controls, as previously described.

While the vibration of the casting mold 35 will facilitate the easy withdrawal of the metal strip 36 from the mold, it may be desirable to introduce a lubricant into the entry end 38 of the mold to form. a film of lubricant between the inner surface of the mold and the surface of the molten metal being cast. As best seen in FIGURE 3, this may be accomplished by providing an annulus 59 in the refractory 6 material 14 of sweep elbow 11 adjacent the entry end 38 of mold 35.

Lubricant is supplied from lubricant tank 60 by lubricant pump 61 through flexible line 62 to passageway 63 opening into annulus 59. The lubricant, which generally is rapeseed oil or linseed oil, is supplied at a pressure of 5 to p.s.i., and the quantity of lubricant introduced into the mold is regulated as a function of the speed at which the slab 36 is withdrawn from the mold.

The startup procedure for the continuous horizontal casting apparatus is performed by inserting a dummy bar (not shown) of suitable cross section through the exit end 3? of the mold up to the entry end 38 of the mold. The dummy bar serves two purposes at this point in that it provides a bottom for the start of the cast, and in addition, it provides the structural strength required to support the thin-walled tubular mold during the period when the fluid coolant 42 is circulated to bring the cooling system up to working temperatures.

After the installation of the dummy bar, the fluid coolant 42 is circulated through the cooling chamber 40 until the coolant pump 42a, coolant flow interrupter 45, and all associated piping are at a temperature slightly above the melting point of the fluid coolant.

During the warmup procedure, the exit end 39 of the mold 35 is sealed with refractory clay so as to prevent a rush-in of air into the vacuum. stream degassing system. The nozzle 24 of the tundish 21 is closed with a fusible plug so that the vacuum system can be brought into operation with a vacuum of approximately .5 millimeter. At this point, a conventional teeming ladle is brought above the tundish 21 and teeming is begun. As the tundish begins to fill, the fusible plug will melt and allow the molten metal to flow into the degassing chamber where it is degassed, as herein described.

The operator then starts the pinch rolls operating at about one-half of the normal withdrawal rate. He then observes the molten level indicator to determine when to increase the withdrawal speed of the pinch rolls to maintain a relatively constant head of molten metal in the degassing chamber 18 of riser 15. As the solidified metal slab 36 is withdrawn, the temperature of the fluid coolant begins to rise. A temperature control will turn off the fuel to the heating and cooling tank or tin pot 42b and begin to introduce cooling water to the coils installed in the tin pot bath to maintain an exit temperature of slightly above the melting point of the coolant.

As soon as the teeming ladle has discharged its molten metal, the teeming crane operator will have a predetermined period in which to position a new teeming ladle over the tundish. However, if the new ladle is delayed, the vacuum degassing system will not be able to function properly as the result of drawing air through the tundish nozzle. This will result in a portion of the slab from the new ladle being cast with a certain degree of honeycomb due to the evolution of gases from the molten metal. As soon as the nozzle is again filled with molten metal, the vacuum system will perform its function of degassing the molten metal.

The design of the casting apparatus is such that it is possible to vary the rate of withdrawal speed over a rather wide range with good casting results.

In the handling of molten steel in ranges above 2,700 E. it is to be expected that there will be refractory and mold failures that will be difficult to anticipate. Accordingly, the casting apparatus is designed with the view of being able to replace all of the equipment which can be subjected to molten steel in a matter of minutes. The horizontally disposed casting housing 10, sweep elbow 11, casting riser 15, and tundish 21 are assembled as a single unit and a complete spare is provided for each operating unit. In the event of a refractory or mold failure, the crane operator will pick up the entire unit and replace it with a spare. Supports for the unit are arranged in such a manner that no bolting, critical alignment, or other time-consuming activities are required. It is necessary only to stop the fluid coolant pump 42a and the lubricant pump 61, disconnect the flexible coolant connnections, the flexible lubricant connection, and the flexible vacuum connection in order to pick up the unit. Thus, the apparatus will have increased availability since the operating unit will not be repaired in place, but will be replaced with a spare.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and described in detail several embodiments and methods of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments and methods illustrate-d. The scope of the invention is pointed out in the appended claims.

I claim:

1. An apparatus for continuous casting of metal, comprising: an open-ended tubular mold; means for con tinuously introducing molten metal into said mold; means for circulating a fluid coolant about said mold for solidifying said molten metal; and a fluid coolant in said circulating means having substantially the same density as the metal being cast.

2. An apparatus for the continuous horizontal casting of molten metal into a solid slab, comprising: a casting housing; a substantially horizontally disposed, elongate, tubular mold in said housing having open entry and exit ends and being supported by said housing at said entry and exit ends; means for introducing the molten metal to be cast into the entry end of said mold; means for circulating a fluid coolant having substantially the same density as the metal being cast between said housing and said tubular mold for supporting said mold intermediate its ends and solidifying said molten metal; and means for withdrawing said slab from said mold.

3. An apparatus for the continuous horizontal casting of metal, comprising: a casting housing; an enlongate peripherally closed, tubular mold in said housing and having open entry and exit ends, said entry and exit ends being rigidly supported by said housing; means for continuously introducing the molten metal to be cast into the entry end of said mold; means for circulating a fluid coolant having substantially the same density as the metal being cast between the housing and the tubular mold for supporting said mold intermediate its ends and freezing said metal into a solid slab; and means for continuously withdrawing said slab from the exit end of said mold.

4. An apparatus for the horizontal casting of molten steel into a continuous solid steel slab, comprising: a housing; a substantially horizontally disposed, elongate, tubular, copper mold having open, flanged entry and exit ends, said mold being rigidly supported at its flanged ends in said housing and having a cross-sectional dimension substantially equal to the size of the slab it is desired to cast; means for continuously introducing molten steel into the entry end of said mold; means for circulating a fluid coolant between said housing and said copper mold for freezing the molten steel in the mold into a solid slab, said fluid coolant comprising a molten mixture of lead and tin having a specific gravity substantially equal to the specific gravity of the steel being cast for supporting said mold intermediate its ends; and means for continuously withdrawing said slab from the exit end of said mold.

5. An apparatus for the continuous horizontal casting of metal, comprising: a housing; a substantially horizontally disposed, open-ended, tubular mold mounted in said housing, said mold having a mold wall and an entry and an exit end; means for introducing molten metal to be cast into the entry end of the mold; means for circulating a fluid coolant between said housing and said mold to freeze the molten metal into a solid; means for intermittently interrupting the circulation of said fluid coolant for imparting a vibration to said mold transversely of its length; and means for continuously withdrawing said solid from the exit end of said mold.

6. An apparatus for the continuous horizontal casting of molten metal into a solid slab, comprising: a casting housing; a substantially horizontally disposed elongate tubular mold mounted in said housing and having open entry and exit ends; a substantially vertically disposed casting riser adjacent the entry end of said mold for providing a head of molten metal for continuously gravity feeding molten metal into the entry end of said mold; means for freezing the molten metal fed into the mold into a solid slab; weight responsive means for indicating the head of molten metal in said riser; and means for controlling the rate of withdrawal of the solidified slab from the exit end of the mold to maintain a desired head of molten metal in the casting riser.

7. An apparatus for continuous casting of metal comprising: an open-ended tubular mold; a cooling jacket surrounding a portion of said tubular mold spaced from the inlet end of said mold, said portion having a deformable mold wall exposed to contact by cooling fluid in said jacket; and means for imparting vibrations to the fluid in said jacket for vibrating and deforming said deformable mold wall normal to the surface of metal being cast in the mold whereby the surface characteristics of the resulting casting are improved.

8. The apparatus of claim 7 wherein said vibration imparting means is means for interrupting and controlling the flow of fluid through said cooling jacket.

9. An apparatus for the continuous horizontal casting of steel into a continuous solid steel slab comprising: a housing; a substantially horizontally disposed, elongate, tubular copper mold having open-flanged entry and exit ends, said mold being rigidly supported at said flanged ends in said housing and having a cross-sectional dimension substantially equal to the size of the slab desired to cast; a substantially vertically disposed casting riser adjacent the entry end of said mold to provide a head of molten metal for continuous gravity feed of a stream of molten metal into the entry end of said mold; vacuum means for degassing said stream of molten metal in said riser; weight responsive means for indicating the head of molten metal in said riser; means for circulating a fluid coolant between said housing and said copper mold for freezing the molten steel in the mold into a solid slab, said fluid coolant comprising a molten mixture of lead and tin having a specific gravity substantially equal to the specific gravity of the steel being cast for supporting said mold intermediate its ends; means for intermittently interrupting the circulation of said fluid coolant for imparting a vibration to said mold transversely of its length; means for continuously withdrawing said slab from the exit end of the mold; and means for controlling the rate of withdrawal of the slab to maintain a desired head of molten metal in the casting riser as indicated by said Weight responsive means.

References Cited by the Examiner UNITED STATES PATENTS 944,370 12/1909 Monnot 22200.l X 2,371,604 3/1945 Brennan 22--57.2 2,641,034 6/1953 Harter 2257.2 2,763,040 9/1956 Korb 22-57.2 2,837,790 6/1958 Rozian 22-57.2 2,997,760 8/ 1961 Hanks et al 2257.2 3,022,552 2/ 1962 Tessmann 2257.2 3,047,915 8/1962 Barnard et al 2257.2

FOREIGN PATENTS 1,340,276 9/ 1963 France.

I. SPENCER OVERHOLSER, Primary Examiner.

R. S. ANNEAR, Assistant Examiner. 

9. AN APPARATUS FOR THE CONTINUOUS HORIZONTAL CASTING OF STEEL INTO A CONTINUOUS SOLID STEEL SLAB COMPRISING: A HOUSING; A SUBSTANTIALLY HORIZONTALLY DISPOSED, ELONGATE, TUBULAR COPPER MOLD HAVING OPEN-FLANGED ENTRY AND EXIT ENDS, SAID MOLD BEING RIGIDLY SUPPORTED AT SAID FLANGED ENDS IN SAID HOUSING AND HAVING A CROSS-SECTIONAL DIMENSION SUBSTANTIALLY EQUAL TO THE SIZE OF THE SLAB DESIRED TO CAST; A SUBSTANTIALLY VERTICALLY DISPOSED CASTING RISER ADJACENT THE ENTRY OF SAID MOLD TO PROVIDE A HEAD OF MOLTEN METAL FOR CONTINUOUS GRAVITY FEED OF A STREAM OF MOLTEN INTO THE ENTRY END OF SAID MOLD; VACUUM MEANS FOR DEGASSING SAID STREAM OF MOLTEN METAL IN SAID RISER; WEIGHT RESPONSIVE MEANS FOR INDICATING THE HEAD OF MOLTEN METAL IN SAID RISER; MEANS FOR CIRCULATING A FLUID COOLANT BETWEEN SAID HOUSING AND SAID COPPER MOLD FOR FREEZING THE MOLTEN STEEL IN THE MOLD INTO A SOLID SLAB, SAID FLUID COOLANT COMPRISING A MOLTEN MIXTURE OF LEAD AND TIN HAVING A SPECIFIC GRAVITY SUBSTANTIALLY EQUAL TO THE SPECIFIC GRAVITY OF THE STEEL BEING CAST FOR SUPPORTING SAID MOLD INTERMEDIATE ITS ENDS; MEANS FOR INTERMITTENTLY INTERRUPTING THE CIRCULATION OF SAID FLUID COOLANT FOR IMPARTING A VIBRATION TO SAID MOLD TRANSVERSELY OF ITS LENGTH; MEANS FOR CONTINUOUSLY WITHDRAWING SAID SLAB FROM THE EXIT END OF THE MOLD; AND MEANS FOR CONTROLLING THE RATE OF WITHDRAWAL OF THE SLAB TO MAINTAIN A DESIRED HEAD OF MOLTEN METAL IN THE CASING RISER AS INDICATED BY SAID WEIGHT RESPONSIVE MEANS. 